Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
H, W = map(int, input().split())
m = [list(input()) for _ in range(H)]
numdot = sum([line.count('.') for line in m])

q = deque([[0, 0, 1]])
m[0][0] = '#'
goal = False
while q:
    i, j, score = q.popleft()
    if i == H-1 and j == W-1:
        goal = True
        break

    for movei, movej in [[1, 0], [-1, 0], [0, 1], [0, -1]]:
        ni = i + movei; nj = j + movej
        if ni < 0 or H <= ni or nj < 0 or W <= nj or m[ni][nj] == '#':
            continue
        m[ni][nj] = '#'
        q.append([ni, nj, score+1])

if goal:
    print(numdot - score)
else:
    print(-1)